LONDON: Internet search leader Google has been forced to change the name of its free Gmail email service in Britain after failing to secure the necessary trademark.

Google has been sparring with UK financial research company Independent International Investment Research (IIIR) since launching Gmail on April 1, 2004 and shaking up the free email market by offering large amounts of storage for free.

Starting Thursday, British users who sign up for Gmail, which has been in a "beta" trial phase since its launch last year, will receive addresses ending in "googlemail.co.uk" rather than "gmail.com." Existing users will be able to keep their current email addresses, the company said.

IIIR's Pronet subsidiary has a Web-based email service called G-Mail. Google did not file a trademark application until its own service had already launched. The two companies have been in heated negotiations to settle the dispute, but they have been unable to reach an agreement.

"This company has been very focused on a monetary settlement," Google said in a statement. "We went back and forth trying to settle on reasonable terms, but the sums of money this company is demanding are exorbitant."

Google has already changed the name of its email service from Gmail to Googlemail in Germany, but said it does not plan to change the name in any other countries.

"Google asked us at one point what it would cost to make the problem go away. We had an independent valuation commission assess what the value of the trademark actually is, but we couldn't reach a settlement," IIIR Chairman and Chief Executive Shane Smith told Reuters.

The IIR-commissioned assessment pegged the value of the Gmail name at a minimum of 25 million pounds ($43.64 million).